Portal 2 review: A hilarious sci-fi puzzle game

Valve originally released "Portal" in 2007, packaged in its "Orange Box" compilation disc which also included "Half Life 2" and "Team Fortress 2." Despite being packaged with such heavy hitting titles and being a relatively short game (the original title could be completed in two to three hours, depending on your ability), "Portal" stood out as the most innovative and critically acclaimed title on the compilation. It was no wonder that work on a stand-alone sequel was announced shortly after the original title's release.

The original "Portal" introduced players to Aperture Laboratories, the handy portal device they developed, and GLaDOS, the lovably masochistic artificial intelligence. As an Aperture test subject, it was the player's task to successfully navigate a series of physics-based puzzles while enduring hilariously negative reinforcement from GLaDOS as she monitored your progress from one test chamber to the next.

The player's primary means of completing each test chamber is, of course, the portal device. This gun-like device is capable of projecting a set of linked doorways onto flat surfaces such as walls, ceilings, or floors. In theory, these doorways - or portals - would allow you to walk in one wall of a room and come out another. Or players could place portals on the ceiling and floor directly above and below them, allowing them to fall infinitely between the two portals. In practice, Valve was much more creative.

The portal device makes its return for "Portal 2," as does GLaDOS, but Valve did more than make an extended version of its original title.

While "Portal 2" retains the use of portals, buttons, switches, and weighted companion cubes to help navigate its gauntlet, Aperture Laboratories has some other toys for us to play with. Most notably, this time around we are introduced to gels. These gels can be used to "paint" surfaces to give them unique properties. The Repulsion Gel will allow you to make surfaces bouncy, while the Propulsion Gel will make surfaces super slick, giving you a speed boost when walking on them. "Portal 2" has you using and combining the tools at your disposal in ways that will have you scratching your head and upon completion have you feeling far more accomplished then a typical videogame.

The story of "Portal 2" picks up an indeterminate amount of time after the original. Not much has changed since your last adventure at Aperture Laboratories, but time has clearly passed. The facility itself shows signs of disrepair and decay and plant life has begun to find a home amid the once pristine walls of the testing center.

While the story certainly isn't as complex as some of the puzzles you'll be solving, it is highly entertaining. This time around the player is allowed to explore parts of the facility outside the usual test chambers. These sections of the game help flesh out some of the history behind Aperture Laboratories and its founder Cave Johnson, voiced by J.K. Simmons.

Stephen Merchant lends his voice to the game as Wheatley, a chirpy and well-intentioned (though dim-witted) personality sphere who serves as the catalyst for the game's story.

The interactions between the player, GLaDOS and Wheatley are what give "Portal 2" its charm and provide much of the humor that keeps the game captivating puzzle after puzzle.

The single player game can be completed in about 10 to 12 hours depending on your ability. This is a good deal longer than its predecessor, but once you're done, you're done. Unlike its predecessor, there are no advanced puzzles or challenges to keep you coming back. Because of this, the single player game never quite hits the same level of difficulty as the original and lacks replay value. Hopefully this will be rectified in the future in the form of downloadable content.

"Portal 2" does feature a robust two-player cooperative mode. In cooperative mode, players take control of two mute bipedal robots, each with their own portal device. As Atlas and P-body, players must complete test chambers specifically designed to promote cooperation and teamwork under GLaDOS's close scrutiny.

Solving physics puzzles that require using four portals instead of the usual two might make your brain hurt more than you're used to when playing videogames, but at least you have a friend to help you.

"Portal 2" is not your typical videogame. It promotes abstract thought and resource management while still delivering a humorous and engaging story and setting. It challenges experienced gamers to think differently about the world in which they're and is a great way for people new to videogames to enjoy a game that asks more of your brain than your hand-eye coordination.

Portal 2 is available on April 19 for Xbox 360, PlayStation 3, PC and Mac. It is rated E10+ for Everyone ages 10+ by the ESRB.